Petroleum derived fuels have been the primary source of energy for over a hundred years. Petroleum, however, has formed over millions of years in nature and is not a renewable source of energy. A significant amount of research in alternative fuels has been ongoing for decades. Within this field, ethanol has been studied intensively as a gasoline substitute and the use of ethanol as transportation fuel has been increasing recently (Gray et al., Curr Opin Chem Biol 2006, 10:141). However, the efficiency of ethanol as a fuel is still in debate (Pimentel, Natural Resources Research 2005, 14:65; Farrell et al., Science 2006, 311:506). There is interest to design several potential alternative fuel molecules other than ethanol, which can be produced biosynthetically, and to develop the biosynthetic pathways for enhanced production of the target fuel molecules using synthetic biology.
This present invention involves the biosynthesis of carboxylic acids and lactones, which can be a source of renewable fuels, using polyketide synthases (PKS).